Forschungsprojekt - SLIM Semizentrale Lüftung und intelligentes Betriebsmonitoring; Teilbericht 1: Kurzfassung und Querschnittsauswertung der Modellprojekte

Abstract

In the research project "Semi-centralised ventilation and intelligent operational monitoring" demonstration projects on semi-centralised ventilation are implemented to gain experience regarding the planning and operational behaviour of semi-centralised ventilation under realworld conditions (sub-reports 1, 2, 3 and 4). At the same time, the replacement of fans in existing systems is being addressed, and a method for determining potential energy savings based on monitoring data is being developed, so called "operating point analysis" (sub-report 5). Semi-centralised ventilation (sL) is an innovative approach to energy-efficient demandcontrolled ventilation, which is particularly suitable for non-residential buildings. The advantage of sL is the reduced fan power consumption. The designs implemented in the demonstration projects show that the ductwork layout for semi-centralised ventilation largely corresponds to that of the conventional variable air volume system with dampers (VSR). Key considerations include preventing air leakage from the exhaust air into the supply air and potential noise emissions from the semi-centralised units. Various solutions were developed and documented for this purpose in the demonstration projects. As part of the research project, HOWATHERM and ebm-papst developed so-called semicentral compact units (SZE). The SZEs contain all the components required for the operation of semi-central ventilation, such as dampers, silencers, fans and airflow measurement. The SZEs were integrated directly into the duct network in the demonstration projects. The extensive monitoring data for the demonstration projects confirm that the semi-central ventilation system operates stably and energy-efficiently. The demand controlled reliably maintains CO concentrations in the indoor air below the setpoint of, for example, 1,000 ppm across the various usage scenarios of the demonstration projects. The energy savings achieved by semi-centralised ventilation depend on the project conditions. Savings of 30% to 40% typically can be achieved in new builds compared to the conventional variable air volume system with dampers (VSR). In existing buildings savings vary greatly depending on the individual case. Overall, it is evident that sL represents a technically and energetically advantageous solution in most applications. The cost-effectiveness is increasingly assured through cost-optimised designs. In 2025, semi-centralised ventilation was included into DIN/TS 18599 and can there for be taken into account to prove the overall efficiency of a building according to the German GEG. The "operating point analysis" makes it possible to quantify the energy savings achieved by replacing fans in existing ventilation systems based measurement data easy to record. The measured operating points are plotted on the performance map of the existing fan and the annual fan power requirement is determined. By projecting the operating points onto the performance map of a more efficient and appropriately sized fan, the corresponding energy savings can be determined. The operating point analysis was successfully tested on five existing systems. In one system, a fan replacement was carried out and the energy savings were determined both mathematically and through measurement. The results are in good agreement. A challenge in assessing the cost-effectiveness is forecasting the investment costs for the fan retrofit. Here, cost functions are subject to significant uncertainties. This sub-report 1 briefly describes the contents of sub-reports 2 to 5. It also presents the demonstration projects for semi-centralised ventilation and compares the key findings in the form of a cross-sectional evaluation. The report concludes with a summary of the findings on semi-centralised ventilation and a conclusion.